David Walsh Blog

• By David WalshNovember 21, 2022

  How to Internationalize Numbers with JavaScript

  Presenting numbers in a readable format takes many forms, from visual charts to simply adding punctuation. Those punctuation, however, are different based on internationalization. Some countries use , for decimal, while others use .. Worried about having to code for all this madness?

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• By David WalshNovember 1, 2022

  Locate Empty Directories from Command Line

  As a software engineer that lives too much of his life on a computer, I like keeping my machine as clean as possible. I don't keep rogue downloaded files and removes apps when I don't need them. Part of keeping a clean, performant system...

• By David WalshOctober 31, 2022

  How to Extend Prototypes with JavaScript

  One of the ideological sticking points of the first JavaScript framework was was extending prototypes vs. wrapping functions. Frameworks like MooTools and Prototype extended prototypes while jQuery and other smaller frameworks did not. Each had their benefits, but ultimately all these years later I still...

• By David WalshOctober 27, 2022

  How to Use window.crypto in Node.js

  I've been writing a bunch of jest tests recently for libraries that use the underlying window.crypto methods like getRandomValues() and window.crypto.subtle key management methods. One problem I run into is that the window.crypto object isn't available, so I need to shim it.To use the window.crypto...

• By David WalshOctober 26, 2022

  Convert Fahrenheit to Celsius with JavaScript

  The United States is one of the last bodies that refuses to implement the Celsius temperature standard. Why? Because we're arrogant and feel like we don't need to change. With that said, if you code for users outside the US, it's important to provide localized weather...

• By David WalshOctober 25, 2022

  Create a Thumbnail From a Video with ffmpeg

  Creating a thumbnail to represent a video is a frequent task when presenting media on a website. I previously created a shell script to create a preview video from a larger video, much like many adult sites provide. Let's view how we can...

• By David WalshOctober 24, 2022

  Detect System Theme Preference Change Using JavaScript

  JavaScript and CSS allow users to detect the user theme preference with CSS' prefers-color-scheme media query. It's standard these days to use that preference to show the dark or light theme on a given website. But what if the user changes their preference...

• By David WalshOctober 19, 2022

  How to Use Storage in Web Extensions

  Working on a web extension is an interesting experience -- you get to taste web while working with special extension APIs. One such API is storage -- the web extension flavor of persistence. Let's explore how you can use session and local storage within...

• By David WalshOctober 10, 2022

  Skip or Only Run a Test with JavaScript Mocha

  Whenever I start to feel anxiety about a big change I'm making, I start writing more unit tests. I'll write down my fear and then write a test that attacks, and eventually relaxes, that fear. There are two actions that I've been frequently using...

• By David WalshOctober 2, 2022

  Determine Default App for File Type from Command Line

  One quality of life improvement any developer can make for themselves is ensuring different file types open in the app they're most proficient in. If you know me, you know I prefer accomplishing as much as possible from the command line. The duti utility...